Doctors and medical professionals have used a variety of substances to control bleeding from cut bone surfaces. Typical materials used for the control of this type of bleeding are bone wax, collagen, oxidized cellulose and thrombin. However, each of these well-known materials has drawbacks in its use as a haemostatic composition. Furthermore, none of these well-known materials possess antibacterial properties.
Bone wax, typically made from a combination of refined beeswax and a softening agent, is brittle at room temperature and requires heat for proper handling. Furthermore, bone wax does not adhere well to cut bone surfaces and is neither biodegradable nor antibacterial. Bone wax is a foreign material that is not readily absorbed by the body, which may interfere with bone regrowth or become a nidus for bacterial contamination.
Collagen is a white, water insoluble fiber typically derived from bovine corium collagen. Collagen has inherent haemostatic properties mostly due to the helical structure of the collagen protein and is absorbed by the body. However, collagen powder is difficult to handle since the powder or fibers stick to wet gloves and form a gel thereon making application to the wound site difficult. Collagen sponges are effective hemostats but do make intimate contact with the wound site. The consistency is too soft for optimal application.
Oxidized cellulose is a solid composition which is soluble in fluids from wounds, forming a sticky mass which readily adheres to wound surfaces. The body absorbs oxidized cellulose. However, oxidized cellulose is insoluble in water and it is reported that moistening with water or saline reduces the haemostatic properties of oxidized cellulose.
Thrombin is a well known clotting agent, but may cause allergic reactions in some individuals. Thrombin also requires mixing with another agent, such as cryoprecipitate or calcium, and also requires a carrier medium. Thrombin has no antibacterial effect.
The use of vancomycin as an antibiotic agent is well known. Vancomycin is a tricyclic glycopeptide antibiotic which interferes with bacterial cell wall synthesis in multiplying microorganisms. Vancomycin is active against gram-positive bacteria, such as Streptococci, Staphylococci, Clostridia, Corynebacteria and Listeria monocytogenes. Vancomycin is particularly used in the treatment of severe staphylococcal infections where other antibiotics cannot be used due to patient intolerance or bacterial drug resistance. Commercially available powdered vancomycin is typically reconstituted in sterile water and the resulting solution is administered intravenously.
Prophylactic topical vancomycin has been proven to prevent sternal wound infections in individuals undergoing median sternotomy for cardiac surgery. Topical antibiotics have been demonstrated to achieve much higher local wound concentrations than systemic (Halasz, Arch Surgery 1977). Topical vancomycin applied to the cut edges of sternum during cardiac surgery results in decreased sternal wound infections (Vander Salm, J Thoracic and Cardiovascular Surgery, 1989). This prospective, randomized clinical trial examined 416 patients and found that the rate of sternal infection decreased by a factor of 7 in individuals who were randomized to topical vancomycin. This represents statistical significance (p=0.02).
Medical literature supports aggressive preventative measure as published reports state that mortality associated with sternal wound infection range from 14–47%. The average cost of individuals with sternal infections is estimated at three times the costs of the original cardiac surgery. Individuals who survive usually require prolonged hospitalization, additional surgical procedures and consequently additional complications and debilities.
What is needed is a haemostatic paste composition that avoids the disadvantages of the pre-existing haemostatic compositions discussed above, that is easily handled by doctors and medical professionals, that readily adheres to cut bone surfaces or open bone fractures, that provides an effective level of haemostasis, that has no systemic or local adverse effect and that provides bacteriostatic and bacteriocidal protection.